Color compensation of optical filter

We're going to end the discussion about filters with this topic that only extremely cautious professional photographers are interested in. Ordinary photographers don't need to use color compensation filters. The purpose of this discussion is not to learn how to use it correctly, but to focus on understanding what it is and how it is designed. Kodak produces all kinds of filters, so that we can adjust a single color at will. These color compensation filters (CC filters for short) can make minor or important adjustments to any kind of light to achieve accurate results. There are six different color compensation filters: color code blue b green g red r cyan c magenta m yellow y each color has many different shades, which are represented by numbers. The larger the number, the darker the color intensity of the filter, from CC025 (lightest) to CC50 (darkest). The relationship between these figures is simple. The color intensity of CC25 is only 1/2 of CC50, and only 1/20 of CC50. CC50Y is a yellow filter with intensity of 05, only 1/4 of CC20Y. The intensity of CC 10R red filter is only 1/3 of that of CC30R, and that of CC5B blue filter is only110 of that of CC50B filter. This is a simple arithmetic relationship. When do I need to use a color compensation filter? As long as we want to change the color or transparency of a photo, we can use a color compensation filter. A common use of color compensation filters is to adjust the special color components of sunlight at different times of the day. We have pointed out that the color temperature of sunlight is 5500K, which is only an approximate value, and it is the average value of sunlight between sunny days 10 and 2 pm. In the morning or evening, the sun is much redder than at noon. For example, the face shot at sunset is too red. In order to adjust to the normal color, we can choose the complementary color filter for the color we want to weaken. If you want to weaken red, because the complementary color of red is cyan (see the color wheel diagram in the film chapter), you should choose cyan filter. As for the strength of the filter, it depends on how much the red color is weakened. If you need to weaken the red color a lot, you can use CC20C or a stronger filter. If it only needs to be slightly weakened, you can use CC 10C or a weaker cyan filter. We can also combine several filters to obtain accurate color changes. But try to reduce the number of filters, because each filter will affect the clarity and contrast of the image, and may even cause glare. How do professional photographers use CC filters? Accurate colors are very important if we shoot as professional photographers. Therefore, professional photographers must be extra cautious and try to eliminate color cast. However, there are many reasons for color cast, such as the type of light source, the brand of film, the factory batch of film (for example, one Ektarom hall producing this batch will not be exactly the same as another batch), the lens (for example, the color reflected by dust on the lens or the color on the lens glass), the conditions of exposure and washing, and so on. Because there are too many influencing factors, professionals try to standardize. They use the same type of light source in the studio, use the same brand of film, buy many films of the same batch at a time, and use the same processing method in the regular darkroom. Most importantly, they will do a lot of experiments. After purchasing a batch of films, shoot them under standardized conditions to see if the effect is off color. If there is a color cast, please choose a CC filter that is complementary to the color cast. According to these tests, the standard filter of this batch of films used under the same conditions was determined. What do professional photographers do when shooting outdoors? Some of these skills are worth learning and applying. First, they measure the color temperature of the light source with a special color temperature meter, and then decide which CC filter to use according to the reading of the color temperature meter. More reliably, in order to test the color, they will take a picture and immediately develop the test results. If there is a color cast, they may decide to go back and shoot again with other CC filters. Should we use CC filter now? Before we are intimidated by these complicated procedures, I remind you: at present, we are still in the training stage, so we don't have to get involved in these processes. First of all, for us, even a little color cast will not invalidate all the photos. Professional photographers, on the other hand, can't be careless, because they are either facing demanding customers or shooting for making magazines or books. Secondly, sometimes a little color cast is even beneficial. For example, the reddish scenery we shoot at dawn or dusk will not arouse people's disgust. It is this reddish color that provides warm tones and soft lighting for many photos, making many photos look more beautiful. This is also the case. Many professional photographers regard morning and afternoon as the prime time of the day. Color temperature meter The color temperature meter measures the relative quantity between different colors of light under specific lighting conditions. This is a very precise, expensive and precise instrument. In order to get the best color effect, photographers often use color temperature tables to accurately use what filters. Such precise information is not necessarily needed in still life photography. The color temperature meter is mainly used for dynamic photography that requires accurate color balance, or it should be used in principle when a scene is illuminated by mixed sunlight and artificial light. Only under such complicated conditions do we need to use a color temperature meter. At this learning stage, we only need to know that various colors of light may exist in different amounts at different times of the day or in different types of artificial light sources. At this time, the color temperature meter can be used to measure the components of various colors.